An ink-jet recording apparatus has been known, which has a recording head for discharging ink as droplets onto a recording paper to print an image. The ink-jet recording apparatus is provided with at least an ink tank containing an ink, to supply the ink from the ink tank to the recording head. In a serial ink-jet recording apparatus, a recording head is mounted to a carriage, so the recording head is moved with the carriage in a widthwise direction of a recording paper, to record an image.
Because the ink is a consumable material, the ink tank is often formed as a cartridge that is removably attached to the ink-jet recording apparatus, so as to make it easy to supplement the ink-jet recording apparatus with the ink. Such a cartridge type ink tank, hereinafter called the ink cartridge, is replaced with another that is fully filled with the ink, when the ink contained in the ink cartridge is used up. For use with the ink cartridge, a carriage of the ink-jet recording apparatus is provided with a cartridge loading portion in a place above a recording head, so the ink cartridge is removably attached to the cartridge loading portion. In many of the ink-jet recording apparatuses, the ink cartridge is placed above the recording head.
Where the ink cartridge is placed above the recording head, it is necessary to keep pressure in an ink chamber of the ink tank or cartridge negative relative to atmospheric pressure. This is because an outlet of each ink ejection nozzle of the recording head, which is connected to the ink chamber, is open to the atmosphere, so the ink will leak out of the outlet of the nozzle due to the weight of the ink, if the ink chamber and the nozzle are not under a negative pressure to the atmosphere. As an easy way to generate a negative pressure in the ink chamber, an ink absorbent is conventionally disposed in the ink chamber. The ink absorbent absorbs and holds the ink by its capillary force.
Meanwhile, the ink cartridge has mainly been made of plastics. After being used up, the ink cartridge is thrown away or collected by its manufacturer or the like for the sake of reusing it. In order to reduce environmental pollution and environmental load, it has been suggested making an ink cartridge of paper. For example, Japanese Laid-open Patent Application No. 10-114082 suggests an ink cartridge that consists of a paper container containing an ink and a casing that holds the paper container and an ink absorbent.
Although the container is made of paper in this prior art, the casing and the ink absorbent are made of other materials than paper. As a material for the ink absorbent, urethane foam is often used. The casing is usually made of plastics. Urethane foam and plastics are both incombustible, and give greater load on the environment in comparison with natural materials like paper. Social demands for reducing the environmental load have recently been increasing, so it is desirable to provide an ink cartridge that reduces the load on the environment.